Another way of venting...if you don't mind drilling glass, is to drill holes in the top of your tank. Several along the front edge and then buy grommets and use no see um mesh. Fruit flies can't escape through the mesh, it looks clean because it is on the top of your tank, not obstructing your front viewing panel. I don't like anything on the front view. Most of us only have that one panel to view through, as we have multiple tanks side by side. I do everything I can to keep that one panel as void as possible of anything that will askew my view. Just find the plastic grommets online that are the size you want and then buy the glass drill bit. I have a big bag of grommets that should last me years and they were very cheap. Just another way to vent your tanks and ultra clean and stealthy. If you have questions just PM me and I can point you in the right direction.